Aromatic polybenzimidazoles (PBI) are characterized by exceptional chemical and short term oxidative stability, excellent thermal and solvent resistance with excellent mechanical properties. A general deficiency, however, is that these polymers have high moisture take-up and tend to be intractable, i.e., not readily soluble or melt processable at moderate temperatures and pressures, wherein fabricating into films, fibers and shaped objects is difficult in many cases. Aromatic polyimides and polyetherimides are thermoplastic polymers which are characterized by good long term thermo-oxidative stability, melt processability, mechanical properties, electric properties and low moisture take-up.
To enhance the processability, reduce cost and moisture takeup of PBI, it is often desirable to blend a thermoplastic polymer with PBI when the ultimate objective is an engineering plastic. While the addition of a thermoplastic polymer will reduce moisture takeup and enhance melt processability of PBI, an excessive amount will often lower thermal resistance and other high temperature properties of the blend resulting in reduced engineering plastic properties.